Drying kiln



R. THELEN.

DRYING KILN.

APPLICATION FILED MAR.2. 1921.

W E K INVENTOR. Ro/f 777e/en A TTORNEYS.

Patented June 20, 1922.

UNITED STATES ROLF THELEN, OF MADISON. WISCONSIN.

DRYING KILN.

Application filed March 2, 1921.

Specification of Letters Patent.

Patented June 20, 1922.

Serial No. 449,194.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. 1).. 625.)

To all 1071 am it may concern:

Be it known that I. ROLF THELEN, a citizen of the United States of America, and an employee of the Department of Agriculture, residing in Madison, \Visconsin, (whose post-office address is Department of :igriculture, Madison, lVisconsin.) have invented a new and useful Dryin Kiln.

This application is made under the act of March 3. 1883, chapter 143 (22 Stat, 625), and the invention herein described and claimed may be used by the Government of the United States, its otiicers and em ployees. and by any person in the United States without payment to me of any royalty thereon. 1 hereby dedicate the same to the free use of the Government and the people of the United States.

This invention. as its name indicates, has to do with a progressive blower kiln in which the direction of air travel through each pile of lumber is periodically reversed, and in which temperature and humidity are automatically controlled to an extent impossible in the present commercial types of progressive kiln.

Referring to the drawings Figure 1 represents a vertical cross section of the kiln and Figure 9. represents a vertical longitudinal section of the kiln, and Figure 3 is a detail of the curtains or partitions. Similar letters refer to similar parts of the drawings. A represents the green or loading end of the kiln and B the dry or discharge end, the lumber moving through the kiln in the direction of the arrow under the letter A in Figure 2. CC represent truck loads oi lumber stacked on edge. In the kiln illustrated there are live stacks of lumber located respectively at stations 1, 2, 3. i, and 5, l igure 2. In the form of edge stacking best adapted to this kiln the boards to be dried are piled on edge with thelongitudiual axis horizontal and the width vertical. Suitable stickers are placed between the individual layers of boards to provide suitable air passages through the lumber pile. D, l), and i represent steam jets tor humidification of the air. G represents the main air inlet duct which is provided with a damper tor the control of the flow of air. H and J represent auxiliary dampered ducts for conditioning the air at stations 2 and 4 respectively. K is the main heating unit and L and M are auxiliary heating units. The arrow N indicates in a general way the path of the air from the cold air inlets through the heating units and lumber piles to the blower O and through it to the atmosphere. The blower (J may be of conventional design and construction and may be driven by any suitable motive power. Pi are curtains or partitions arranged to constrain the air moveuicnt in the desired path. root oi the kiln. The partitions P can be of any conventional design so arranged that the air cannot pass from one lumber pile to the next except over the top as between stations 1. and 2 or underneath as between stations 2 and 2-3. A specific design of partition is shown in Figure 3. R is a flexible curtain or flap fastened to the ceiling Q, and S is a plate secured between the lumber piles CO. This type of partition permits the trucks to be moved through the kiln without interference. The plates S extend continuously around the space between each two trucks and the flaps R are secured to the floor and side walls of the kiln between each two stations and also to the ceiling between alternate stations. In the design illustrated they are located between stations 2 and 3 and between stations 4 and 5 leaving a free passage over the tops of the trucks between stations I and 2 and between stations 3 and 4.

The operation of the kiln varies but slightly from that of the ordinary progressive kiln. The truck loads of lumber are moved progressively from the green end A toward the dry end B, suitable rails and other necessary means being provided for this purpose. The air moves upward through each pile at stations 1, 3 and 5, and (lO\\'I'lWL1l'd at stations 2 and 4. Thus the direction of air travel is reversed each time the truck is moved forward one station. 'lemperature and humidity are controlled at the dry end by means of the main heating unit K and the steam jet pipe D. After passing through two piles of lumber, the temperature and humidity may be again controlled or regulated by means of the auxiliary heater L, the steam jet pipe E and the damper-ed cold air inlet H. Similar control is secured at successive intervals of two piles until the green end. of the kiln is reached. Under ordinary conditions it is expected that the adjustments at the points Q represents the of ire-conditioning will be practically permanent.

The advantages of the type of kiln described, and embodied in this invention, are,

in brief as follows: Positive air circulation past both broad surfaces 0t every board in the kiln; reversible circulation, which pro duees much more uniform dryingthan circulation in one direction only; absolute control of temperature and humidity throughout the kiln; ample circulation with the eonsequent great increase in the drying rate. In addition to these unique advantages, the kiln also has the well-recognized advantages of the present types of progressive kiln among which are great heat eliieieney, great capacity possible in a single unit, simplicity oit control in that conditions on ee established remain set indefinitely and abilit to absorb green stock and deliver dry stovk at a practically continuous rate.

1 claim 1. The combination with. a progressive drying kiln provided with suitable means for the movementthrough the kiln of the material being dried, said material being edge-staeked crosswise on suitable trucks, of

an exhauster fan means for driving said fan, air bafiles means for conditioning the air upon entering the kiln, and means for conditioning said air after each. downward pass.

2. In a progressive drying kiln means for producing an air oiri' ulat-ion passing alternately upward and downward through adjacent truck-loads of material, being dried and passing progressively from the dry end to the green end of the kiln combined with means for conditioning the air upon entering the kiln.

2;. In a progressive drying kiln, means for producing an air circulation passing alternately upward and downward through adjacent truck-loads o'lt' mz'i-terial being dried and passing progressivel5 from the dry end to the green end of the kiln, combined with means for conditioning the airupon entering the kiln and means 'i'or conditioning said air at intervals during its passage through the kiln.

ROLF TT TELEN. Witnesses ARTHUR- KoEHLnn, HARRY D. TIEMANN. 

